There are many phones out there in different shapes, sizes and capabilities. Prices of phones are usually based on its performance and quality.
When you go to market to purchase a phone, the main question you should ask yourself is:
What do I really need a phone for?
If you just need a phone mainly to make calls and send text messages, then you are better off with a low end phone. They are available in various shapes, sizes and quality and are generally cheap. You can get one of these phones starting from $10.
If you want to be able to do more with your phone like take cool pictures, shoot video clips, create short videos, browse the internet, lite typing work on Ms word/docs, then you are better off with a mid range Android or iphone. You can get one of these phones for as low as $65 and as high as $350 .
If you are the type that wants to do premium stuff with your phone, like play high end games, shoot high resolution and 4k videos, shoot stunning cinematic pictures, video editing, machine learning and so on, then you are better off with a high end Android or iphone. These types of phones can be as low as $400 to as high as $2000.